Question

A sphere, a cylinder and a cone are
of same radius and same height.
The ratio of their curved surface
area is​

Answer 1

Step-by-step explanation:

Since, the height of a sphere is the diameter, the cone and cylinder have height 2r. 

Then 

Curved surface area of Sphere=4πr²

Curved surface area of cylinder =2πr(2r)=4πr²

Curved surface area of cone = πrl

where, l=(r2+h2)=(r2+(2r)2)=5r2=r5

⇒ Curved surface area of cone =π5r2

Now, 

ratio of CSA 's a sphere ,cylinder and a cone = 4πr2:2πrh:πrl

=4πr2:4πr2:πr25

=4:4:5